Rare dementia is a tricky concept. Currently, there are people living in the UK who have been diagnosed with dementia but have a really different and very rare outcome. The controversy about their unusual pathway sometimes degenerates into an angry exchange of insults.

One theory is that these people have been misdiagnosed. That theory is that they have a functional cognitive disorder which is not dementia. No one is denying that they have genuine neurological symptoms, but they differ from what is usually regarded as dementia. Usually dementia is progressive, debilitating and disabling. Those unusual people may have been living with a dementia diagnosis for a decade or more, travelling the world, writing books, taking part in political action, talking on radio and television. They are very unusual because they continue to function relatively well. The “functional” nature of their illness is that they don’t have the deterioration in the brain tissues that are seen in “organic” illness, through scans and other tests. It’s been described like a computer problem. Your problem in a computer can be in the hardware or the software. Typical dementia is a hardware problem where the damage can be seen. A software problem is one where the problem is real, but you can’t find anything physically wrong with the equipment.

To question a diagnosis is seen and felt by some as extremely insulting

But to question their diagnosis is seen and felt by some as extremely insulting. Those asking questions get described as “dementia deniers”: echoing the disreputable people who want to negate established facts of war atrocities. This is a violent response to justifiable questions such as…. Why do some people with dementia live relatively normal lives? Why are they in a stable state for many years, when the majority go down hill quite fast, soon becoming totally dependent on their families and friends? I’ve even seen one angry person respond to a doctor by saying that he’s such a bad doctor, his patients probably go down hill fast because of him and it’s due to his ignorance that he’s never seen a person “living well with dementia”. Mistakes may have made in the early stage of the illness, but “undiagnosing” dementia is very difficult both for the clinician and the patient.

On the other hand, there are some forms of dementia that are organic and visible in forms of brain damage, but they are still rare. This is difficult for both clinicians and patients. If it is a kind of dementia that you’ve never seen, it is hard to diagnose it. Not getting a diagnosis means that it’s impossible to plan. Sometimes a diagnosis, however serious, is a relief in itself. This includes conditions such as posterior cortical atrophy, and progressive non-fluent aphasia.

Through the Disruption Awards, the Dementia Trust has been able to support the creation of resources for people with rare dementias.

The work done in the Dementia Research Centre at UCL is outstanding, and builds on the real experience of people with dementia and those who care for them.